A traditional motorcycle comprises a gas knob (conventionally the knob set to the right of the handlebar), which is rotatably mounted and is mechanically connected to a control of the engine that regulates generation of the torque. Normally, the gas knob is connected to the control of the engine by means of at least one metal cable of a Bowden type, which is inserted within an external sheath to slide with respect to the sheath itself and is pushed by a spring towards a resting position corresponding to a zero torque.
Recently, drawing upon the experience accumulated in the automotive sector, also in motorcycles there has been proposed the application of drive-by-wire (DBW) systems, in which the gas knob is no longer mechanically connected with the control of the engine, but is only connected with a position sensor that detects the position of the gas knob and consequently drives an actuator that acts mechanically on the control of the engine.
The greater problems that must be faced in the design of a DBW system suited for being used in a motorcycle is the production of an acquisition system for detecting the angular position of the gas knob. In fact, said acquisition system must be able to interpret rapidly and without any possibility of error the intention of the driver to accelerate/decelerate, must provide an information redundancy such as to render certain the interpretation of the intention of the driver by an electronic control unit for controlling the engine, and must be installable in the context of a motorcycle, taking into account the problems linked to the encumbrance, the high level of vibrations that may occur in a motorcycle, and the adverse environmental conditions linked to the absence of protection (accidental bumps, very low or very high temperature, splashes of water, etc.).
Furthermore, an acquisition system suitable for being used in a motorcycle must be extremely versatile in order to be readily integratable in motorcycles that are even very different from one another in so far as the production of motorcycles is very fragmented and characterized by a vast production of models frequently with small volumes.
In the automotive sector, there exist different solutions for making an acquisition system for detecting the position of the pedal of the gas. However, said solutions for automobiles cannot be used for a motorcycle since it is too cumbersome and not sufficiently robust. Furthermore, in motorcycle applications the reliability and rapidity in interpreting the intentions of the driver is even more important than in automobile applications in so far as an automobile resting on four wheels is intrinsically stable and hence in driving an automobile it is tolerable (i.e., it is not substantially dangerous) for there to be a brief deviation between the torque supplied and the intention of the driver. Instead, a motorcycle, given that it rests just on two wheels, is intrinsically unstable and is based upon a dynamic equilibrium that can be readily upset also by a brief deviation between the torque supplied and the intention of the driver (particularly during limit conditions, such as on a bend).
EP1338500A1 discloses a sensor for detecting a throttle grip rotation and comprising a detect shaft rotatable about an axis in conjunction with a throttle grip, a pair of rotation terminals rotatable together with the detect shaft, contact pieces disposed on each of the rotation terminals, a printed circuit including conducting pattern portions printed along sliding loci of the contact pieces and a resistance portion printed in a sliding range of the contact piece of the conducting pattern portion for generating a resistance against a current flowing in the conducting pattern portion.
EP1600320A1 discloses an accelerator opening degree detecting apparatus for a motorcycle; a shaft is rotatably supported to a fixed member, an accelerator opening degree sensor is arranged in one end of the shaft, a rotating drum is arranged in the other end, the rotating drum and an accelerator grip are coupled by a coupling member, and the accelerator grip and the rotating drum are synchronously rotated.